And the Lord said to Moses and Aaron, "This is the statute of the Passover: no foreigner shall eat of it,  but every slave that is bought for money may eat of it after you have circumcised him.  No foreigner or hired servant may eat of it.  It shall be eaten in one house; you shall not take any of the flesh outside the house, and you shall not break any of its bones.  All the congregation of Israel shall keep it.  If a stranger shall sojourn with you and would keep the Passover to the Lord, let all his males be circumcised. Then he may come near and keep it; he shall be as a native of the land. But no uncircumcised person shall eat of it.  There shall be one law for the native and for the stranger who sojourns among you." (Exodus 12:43-49 (ESV)
“And you shall nor break any of its bones,” these word’s jumped off the page for me the other day. My mind went racing and all the sudden I began thinking, “For these things took place that the Scripture might be fulfilled: "Not one of his bones will be broken." (John 19:36 (ESV) And after that connection came “Cleanse out the old leaven that you may be a new lump, as you really are unleavened. For Christ, our Passover lamb, has been sacrificed.” (1 Cor. 5:7 (ESV)
The importance of Christ’s bones not being broken become absolutely clear, if they were broken then Christ could not have been our Passover lamb. So just as circumcision finds its New Testament correlation in baptism, (Col. 2), The Passover, which was the center of Jewish life, the culmination of the sacrifices of the Old Testament, indeed the foundation of the sacrificial system of the Old Testament, finds it’s correlation in the Lord’s Supper, where Christians eat their Passover lamb, the body of Christ, because the Passover lamb must be eaten. “Your lamb shall be without blemish, a male a year old. You may take it from the sheep or from the goats,  and you shall keep it until the fourteenth day of this month, when the whole assembly of the congregation of Israel shall kill their lambs at twilight.  "Then they shall take some of the blood and put it on the two doorposts and the lintel of the houses in which they eat it.  They shall eat the flesh that night, roasted on the fire; with unleavened bread and bitter herbs they shall eat it.  Do not eat any of it raw or boiled in water, but roasted, its head with its legs and its inner parts.  And you shall let none of it remain until the morning; anything that remains until the morning you shall burn.” (Exodus 12:5-10 (ESV)
This is fundamental to understanding the Lord’s Supper. Just as the church is the new Israel, so the Lord’s Supper is our Passover feast, it continues weekly and even daily as the Passover feast continued daily and weekly in the rest of the sacrifices offered at that temple. Whatever these sacrifices were, they found their ultimate meaning in the Passover, the foundational sacrificial feast of the Nation of Israel, a feast of victory in which they celebrated their deliverance from Egypt and their salvation in God. And it was to be eaten.
This is foreign to our concept of sacrifice. In western thought, where for so long there have been no sacrifices, it is common to think of sacrifice as giving something up, giving something to God, and thereby relinquishing use of it ourselves. But this is not the concept of sacrifice in the Old Testament. In fact most all sacrifices of the Old Testament were consumed by either the priest, or the laity or both. The obvious exception to this is the burnt offering that was consumed in total by God, through his holy fire on the altar, the only altar where sacrifices could be offered. But only by consuming the sacrifice could a person participate in the sacrifice and thereby benefit from the sacrifice. The idea being one of sharing a meal with God, eating in his presence, and by eating the food he sanctified with his holiness the all consuming fire of the altar, his holiness was communicated to the person who offered it. Far from giving it up, one was making maximum use of it, not only finding earthly nourishment, but nourishing his soul with the Holiness of God. (All this is explained much better by Kleinig’s commentary on Leviticus).
But then there comes the rest of this institution. The Passover Lamb was not allowed to be eaten by just anyone! Neither is the Lord’s Supper. There are rules and regulations. First and foremost in importance those who participated in the Lord’s Supper had to be circumcised, assuming they were males, and had to be at a very minimum members of the family of a circumcised man of Israel if they were not. It was not open to the uncircumcised. So the Lord’s Supper is not open to those who have not been baptized.
Second it was to be celebrated in the family. “No foreigner or hired servant may eat of it. It shall be eaten in one house; you shall not take any of the flesh outside the house.” And it shall be eaten by everyone of the house. Congregation under the spiritual fatherhood of the pastor, ( For though you have countless guides in Christ, you do not have many fathers. For I became your father in Christ Jesus through the gospel. (1 Cor. 4:15 (ESV) That is there is warrant for the practice of calling a pastor father, despite the saying of Christ in Matthew that was dealing with something entirely different, and if taken to literally would make the fourth commandment unintelligible. But the congregation of Christians gathered together takes on this character of family as the people who partake of communion at that altar confess their oneness with each other, and are under the spiritual fatherhood of the pastor, having confessed their unity with the congregation when they became members. And just as the foreigner could participate as a house guest if he and ALL his males were circumcised, so those visiting from other congregations that share the same confession of faith are able to commune with them at the altar. But those outside the common confession that marks the family of Israel are asked to refrain from participating.
Perhaps though this also gives warrant for reconsidering the practice of communing children, as everyone in the house of an Israelite that could handle eating solid food would have been expected to participate in the Passover feast, and then been instructed in its meaning as they grew up in that house, so perhaps the same thought should guard our concerns with the Lord’s supper, that those children who have been baptized, and are members of the congregation receive their Passover lamb, and the blessings given therein, as they grow to discern the body and blood of the Lord.